Here is one of the world’s rarest and strangest fish, the golden cave catfish (Clarias cavernicola) which can be found only one place on Earth, the Algamas/Dragonsbreath cave in the Namib Desert.  This incredible cavern is 100 meters (300 feet) beneath the desert and it holds the world’s largest known underground lake (discounting all subglacial lakes—which can be huge).  Above ground is an arid desert wasteland, but in cave is a huge lake where unfathomed waters may descend another 100 meters into the Earth.  Since only a narrow chasm opens to the sky, the lake has a very limited ecosystem built around whatever falls into this chasm (which was only discovered by science in 1986).  These blind ascetic catfish dwell on such scraps and on the white shrimp and strange aquatic worms which live in the water beneath the desert.  Though they have lost their eyes, their other senses have become extremely acute in order to find every bug or speck of nutrient which falls into the hidden lake.  Additionally, these small (16 cm/6 inch) fish have a limited ability to sip air–so that they can better survive the still and anaerobic depths of their hidden lake. The entire species may only consist of a few hundred (or thousand) individuals.